# Utility of Carboxyhemoglobin Level for the Diagnosis of Invasive Bacterial Infection in a Febrile Neonate at Paediatric Emergency Department

## TL;DR

This study explores whether carboxyhemoglobin levels can help diagnose bacterial infections in febrile neonates at the emergency department.

## Contribution

This is the first study to examine COHb as a biomarker for invasive bacterial infections in a pediatric emergency setting.

## Key findings

- A COHb level ≥1.4% has 74% sensitivity and 69% specificity for diagnosing invasive bacterial infections.
- COHb remains a strong independent predictor after adjusting for confounding factors like birth weight and gestational age.
- The study suggests COHb may be a useful biochemical marker for risk stratification in febrile neonates.

## Abstract

Carboxyhaemoglobin (COHb), which represents the fraction of carbon monoxide bound to haemoglobin, is available as a point-of-care test in the emergency department. This study aimed to assess the role of COHb in the diagnosis of invasive bacterial infections (IBI) in a paediatric emergency department.

This retrospective study examined a single reading of venous COHb values in otherwise healthy neonates who presented with febrile illness at the paediatric emergency department at Royal Hospital, Muscat, Oman, between December 2019 and December 2022. The optimal COHb level for the diagnosis of IBI was determined using receiver operating characteristic curve analysis. Multivariate regression analysis was applied to assess the effect of age, birth weight and sex as cofounders for the diagnosis.

A total of 336 neonates presented to the paediatric emergency department with febrile illnesses and 201 neonates met the inclusion criteria; 43 neonates were culture-confirmed to have IBI. A COHb level ≥1.4% carries a sensitivity of 74% and a specificity of 69% for the diagnosis of IBI. Moreover, it was strongly independent of the diagnosis when adjusted for the confounding factors of birth weight, sex, pediatric early warning score, type of admission and gestational age (odds ratio = 6.080, 95% confidence interval: 2.810–13.155; P <0.001).

This is the first study to examine COHb as a biomarker for IBI in a pediatric emergency setting. COHb may be a useful biochemical marker for risk stratification in febrile neonates. Further studies are required to better delineate its clinical utility.